Authentication of a user to a device has been accomplished using a variety of biometric or user provided inputs. For example, a user may enter a password in to a smart phone to access functionality of the smart phone. However, the mere entry of memorized characters raises potential concerns for an ease of duplication and also a potential for forgetting/losing the specific sequence of characters to be entered.
Biometric authentication provides an alternative means for authenticating a user. However, various biometric authentication technologies are cumbersome to implement on a consumer device as a result of space constraints, cost constraints, and other limitations. Further, false positive and false negative authorizations may frustrate a user as a result of environmental changes (e.g., lighting, humidity, environmental noise) and physical changes of the user (e.g., hair changes, accessories, angle of view).